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nanoPHYS’12 – December 17-19, 2012
K. Nakano, S. Miyasaka, K. Nagai and S. Obata (Department of Physics, Tokyo Institute of Technology)
Drift Chambers
12 cm
2 cm
Construction of New St. 3– Chamber
Performance Requirements
SeaQuest Spectrometer
Summary & Plan
Construction of Drift Chambers forDrell-Yan Measurement at FNAL SeaQuest
For Details & Commissioning Status … Poster by F. Sanftl
St. 3+ & St. 3– Chambers Structure – St. 3+ DC & New St. 3– DC
New St. 3– chamber is being constructed at FNAL toward the physics run.
Measuring Wire Tensions
Stretching Wires
Drift Property
Detection Efficiency
Hit distribution
Procedures
What’s Measured
• Muon pairs from Drell-Yan process• Momentum ~ 30 GeV/c Solid Iron:
Focusing
Magnet, Hadron
absorber and
beam dump
Iron Wall:
Hadron
Absorber
Station 1:
Hodoscope
array
Wire chamber
Station 4:
Hodoscope
array
Prop. tube
Station 2:
Hodoscope
array
Wire chamberLiquid H2, D2
& solid
targets
Station 3:
Hodoscope
array
Wire chamber
KTeV magnet:
Momentum
meas.
Proton
beam
120 GeV
Drell-Yan Process in Proton-Proton Reaction
• Front view
• Position & direction of sense wires• 6 planes• 14o tilt in U & V
• Cell structure
Guard wire
Sense wire
Field wire
Cathode wire
Muons
• Position resolution : 400 micron in horizon direction• Muons are bent in horizontal plane
• Rate tolerance : upto 1 kHz in wire length of 1 mm• Backgrounds due to muons from J/psi decay
>> Drell-Yan signals
Operation
• Gas : Argon (86%) + Methane (10%) + CF4 (4%)• HV : –2.4 kV (cathode & field), –1.4 kV (guard)
• Beam experiment for commissioning … March & April of 2012• Spectrometer upgrade … Now• Beam experiment for physics … Spring of 2013
Experiment Schedule
St. 3+ chamber has been tested• With the commissioning beam• With cosmic rays and a test chamber at Tokyo Tech
2012 02 Constructed the frame parts @ Japan
03 Transported the frame parts to Fermilab
06 Assembled the frame
07-10 Stretched all wires
11-12 Build & attach the Mylar windows / Start gas flow
2013 1-2 Build & attach the electronics for readout & HV / Start HV training
3 Test
4 ? Start the physics run
• Measurement with the commissioning beam
• With & without hodoscope hitsbeing matched
• GEANT4 simulation• Several mass ranges … J/psi,
D-Y near J/psi, D-Y w/ high mass, etc.
• To be compared with measurement• Dimuons from Drell-Yan, J/psi, Upsilons
• Measure the eigen frequency ( ) of wire free oscillation• External pulse w/ initiates the oscillation• Oscillation is detected as induced voltage• Amplitude gets maximum @
• Derive tension ( ) from by• • Accuracy: 0.5%
• 5,154 wires … 768 of sense wires & 4386 of other wires• Optimized procedure• 2 minutes/wire• 4 hour/shift x 2 shifts/day x 2 months
• Tension of wires• Adjusted by a metal block hanged• 75 gf for sense wires & 130 gf for other wires• Accuracy: 10% required & 5% (@ 3s) achieved!!
• SeaQuest measures Drell-Yan process, , in proton-proton reaction with 120 GeV proton beam at FNAL
• SeaQueast Japanese group constructs & operates two drift chambers at Station 3 (St. 3+, St. 3– )• The detail of the chamber characteristics are shown above
• St. 3+ chamber has been tested with the commissioning beam and with cosmic rays and test chamber at Tokyo Tech
• New St.3– chamber is being constructed at FNAL toward the physics run
SeaQuest Japanese group constructs & operates two drift chambers at Station 3 (St. 3+ & St. 3– )
• Wire• Sense : Au-W(Re), f30 mm• Others : Au-CuBe, f80 mm
• Measurement with test chamber & Ar:CO2 ( 80% : 20% )• Definition: efficiency of detecting one track by one plane
• Track coincidence of two scintillators covering 10 cm (5 wires) × 18 cm
• Efficient event one (or more) of wires in layerhas hit
• Efficiency ~ 100% within uncertainty at HV > 2.65 kV
• Spectrometer is being upgraded now for higher beam rate (× 10) in physics run• Detectors … St. 1 & St. 3– chambers• Beam … monitor & intensity stabilizer• Data acquisition … fast throughput
• A beam experiment for physics will start in Spring of 2013
• Measurement with test chamber & Ar:CO2 ( 80% : 20% )• Relation between drift distance & drift time
• Drift velocity ~ 30 micron/ns• Consistent with Garfield simulation
• Position resolution = event-by-event drift-time deviation 500 micron
Performance of St. 3+ Chamber
5 m × 5 m × 25 m